Ram impactor



F. P. ROBBINS Sept. 3, 1968 RAM IMPACTOR Filed June 27, 1966 v 3 .N n?

S mm m% :Y W 0 R K m R DB nu F )5 bw mu 2 OE United States Patent 3,399,928' RAM IMPACTOR Frederick P. Robbins, 224- S. Michigan Ave.,

Chicago, 111. 60604 Filed June 27, 1966, Ser. No. 560,569

2 Claims. (Cl. 29937) ABSTRACT OF THE DISCLOSURE Ram impactor with bit having anvil-forming shoulder to receive impact of heavy mass hammer slidably suspended about bit shank by coil spring in axial cavity in hammer.

The present invention relates in general to impactors, and has more particular reference to a mechanical bit or tool head forming a drop hammer adapted for use in forging, chipping, demolition work, earth and concrete breaking, and the like.

An important object of the invention is to provide a drop hammer or impactor having a pair of relatively movable parts adapted to be impactingly applied by gravity, or other force action, upon a body of work substance in order to crack, crumble or break up the body, the impactor embodying a bit element for engaging the work substance, and an inertial hammer element resiliently suspended upon the bit, and, hence, supported thereon in retracted position, whereby to apply a delayed blow or ram impact upon the bit after it shall have become embedded in the work substance.

Briefly stated, impactors embodying the present invention may comprise a bit having a working end shaped for penetration into a body of work material to be broken, and a body of heavy material, such as cast steel, forming a ram or hammer, supported in retracted position on and behind the bit element, as by means of a spring, so that, after the latter shall have been thrust into the work material, either by gravity or by some other bit thrusting force, the momentum applied to the impactor as a whole will cause the hammer to compress its supporting spring and rammingly impact upon an anvil portion of the bit, to force it into the work material and increase its material splitting and crumbling action, the suspension spring being selected with regard to the weight of the. hammer so that the same will normally be held in retracted position while the impactor is being dropped, as by gravity, or otherwise thrust upon the work material; but the spring is s ufiiciently flexible to permit the hammer to freely impact upon the bit when the same shall have ceased its initial penetration into the work material.

The foregoing and numerous other .important objects, advantages and inherent functions-of the invention will become apparent as the same is more fully understood from the following description, which, taken in conjunction withthe accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings:

,FIG. 1 is a partially sectionalized side view of a ram impactor embodying the ,presentinvention, the parts being shown in normal position with hammer or ram fully retracted from the bit element, before impact of the tool with a body of work material to be broken;

FIG. 2 is a view similar to FIG. 1 showing the relative position of the parts of the device immediately following impact with a body of work material;

FIG, 3 is a view similar to FIGS. 1 and 2 showing the hammer at the instant of striking its ramming blow upon the anvil portion of the. bit; and

FIG. 4 is a perspective view of the device illustrating 3,399,928 Patented Sept. 3, 1968 its action when the work material affords no resistance, but crumbles so freely that the hammer is unable to impact upon the anvil portion of the bit.

To illustrate the invention, the drawings show a ram impactor comprising a bit 11 and a bit impacting hammer 13 suspended on the bit element by means of a spring 15. The bit 11 may be made of tool steel, or other suitable material, and may comprise a head 17 of any suitable or preferred configuration providing a lower work engaging and breaking end 19 adapted to bite into, crack, split or crumble a body of work material 21, such as a pavement to be broken up, or other formation to be cracked, split or otherwise demolished, the opposite or upper end of the head 17 providing a shoulder 23 forming an anvil in position to receive the impact of the striking end of the hammer 13. The head 17 may be provided with a suspension stem or shaft 25 secured upon and preferably in coaxial alignment with the head of the bit, said stem extending upwardly of the anvil 23.

The ram or hammer 13 may conveniently comprise an elongated preferably cylindrical body 27 of heavy, ponderous material, such as steel or iron, which may be provided with an axial channel 29 sized to snugly, yet freely slidably receive the stem 25, so that the body 27 is free to move longitudinally of and on the stem. The lower end of the body 27 may be formed with a pocket or cavity 31, in coaxial alignment with the channel 29 and opening at the lower end of the body, said body outwardly of the open end of the cavity 31 forming a circular ram face 33 in position to strike upon the anvil 23 of the bit, when the momentum of the body 27 compresses the spring, after the bit has engaged with the Work material 21.

The spring 15 preferably is of helical configuration and is assembled in position embracing the stem 25 within the cavity 31. The spring 15, at one end, may bear upon the inner end of the cavity 31, around the channel 29. At its other end, the spring 15 may bear upon a sleeve or bushing 35, which snugly embraces the lower .or bit connected end of the stem 25, the bushing 35 being sized to fit slidingly within the open end of the cavity 31. The upper end of the stern projects upwardly of the ram or hammer 27, and is provided with an outstanding, preferably circular flange 37 adapted to engage the upper end of the body 27, when the same is in fully retracted position on the stem 25, the upper end of the bushing 35, when the body 27 is in such retracted position, preferably extending within the open end of the cavity 31. The upper end of the stem 25, outwardly of the body 27, may also be provided with suitable means such as the ring or clevis 39 for suspending the ram impactor on a carrying line or rope, by means of which the tool may be raised to a desired elevation above the body of work material to be broken, and then permitted to fall upon it.

The gravity accelerated free fall of the tool through a predetermined distance onto a body of work material, such as paved or other ground strata, or other structural to be broken, automatically imparts a shock wave strain on the work material tending to shatter the same. The equilibrium condition of the components of the tool, as when in free suspension on a carrying line, is shown in FIG. 1. The back stop flange 37 holds the ram body 27 in fully retracted position, with the spring 15 preferably held under minimal compressive stress. When the tool is permitted to drop upon a work body to be broken, depending upon the distance through which it is permitted to fall, the tool will attain a desired velocity; and when the bit encounters resistance to its falling movement, upon engagement with the work material 21, the momentum of the ram or hammer 27 compresses the spring,

r 3 which in turn presses the bushing 35 and the bit head end 19 further into the work material 21 through its yielding upper layer 41, and upon any relatively non-yielding lower strata 43, such as concrete, thereby setting u a shear stress vector 45 in the work material. As the momentum of the body 27 further compresses the spring 15, and thus increases the static pressure of the bit upon the stratum 43, the ram and anvil faces 23 and 33 are brought forcefully together, thereby producing a dynamic, shattering shear wave 47 in the work material.

The ram impactor automatically compresses the spring and pushes it onto the bit, thereby press-seating the tool through any shock absorbing soft cover strata, such as asphalt, gravel, or the like, thereby impinging the bit upon the real work resistance. If the work load resists sufficiently, the ram 13 bottoms out directly upon the fully stressed bit. This ram impact induces a shock wave through the statically stressed bit to yield a dynamic strain of much greater work effectiveness than the simple drop of a hammer of equal mass and momentum. A dynamic shearing is thus attained in the body of work material, at the peak of static compressive stressing. Where this static stressing is sufficient to overcome the work resistance, without impacting or bottoming the hammer or ram 27 upon the bit, the spring may then react as a shock absorber as indicated in FIG. 4, thereby preventing the mechanism from shattering itself when the work fails to absorb the impact. Conventional power driven paving breakers, diesel operated pile hammers, and

the like require automatic locking mechanisms to keep from firing when operated in the absence of a load of sufficient magnitude to accept the operating stroke or blow.

Conventional mechanical hammers induce an additive, rather than a compounded reaction, upon the work material, that is to say, they first impact and then press the work material. The device of the present invention first statically presses the bit into the work load, and then, at the peak of this static stressing, rams a heavy, dynamic, shattering shock wave upon the work material. The factors of mass, velocity, spring strength of the device all react to produce the desired result; however, it is thought that the progressive application of these factors contribute to the value and success of the present invention, in that it automatically applies the required progression and timed reactions of static and dynamic forces into whatever resistance may be provided by the work substance, without other mechanisms, mechanics or resettings. 1

In die forging practice, the final blanking of the stock, to squash it flat enough to allow terminal contact between the ram and anvil dies, requires an anvil base weighing some twenty times the mass of the ram, to absorb the shock wave produced by the terminal touch of the ram pistons upon the anvil die. All sorts of expedients have been employed to avoid, or to contain such unwanted destructive reaction. The object of the present invention is to produce and magnify such destructive shock wave and to apply the same where it will produce the maximum desired work, as in demolition of structural bodies and in the fracturing of mining strata.

It is thought that the invention and its numerous attendant advantages will be fully understood from the following description, and it is obvious that various changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of demonstrating the invention.

The invention is hereby claimed as follows:

1. A ram impactor comprising an impact member having a lower end adapted to be thrust against and penetrated into a body of work material, a stem extending outwardly from the opposite end of said impact member, an anvil-forming shoulder on said opposite end of said impact member about said stem, a hammer of ponderous mass having an axial, elongated channel in the upperportion thereof matingly, slidably receiving said stem and slidably mounting said hammer on said stem, said shoulder facing the lower end of said hammer in position to receive the impact of the lower end of said hammer thereon, the lower end of said hammer having a cavity coaxial with said channel, of larger transverse cross-section than said stem and said channel, and opening toward said anvil-forming shoulder, and a spring surrounding said stern and extending in said cavity, one end of said spring bearing upon the bottom of said cavity and its opposite end being supported on said impact member, said spring resiliently supporting said hammer in spaced relationship to said shoulder and adapted to resiliently yield sufficiently, upon impact of said impact member against a body of work material, to allow said hammer to strike said shoulder after said impact of said impact member against said body.

2. A ram impactor as set forth in claim 1, including a bushing, snugly surrounding the stem at its junction with the impact member, for supporting the spring in operative position on the stem, said stem and hammer having cooperating stop means limiting the movement of the hammer on the stem in a direction away from the impact member, whereby the hammer is normally supported on the stem, with said spring slightly compressed, said bushing being sized to extend within the open end of the cavity when the hammer is in its position of maximum retraction away from the impact member.

References Cited UNITED STATES PATENTS 1,863.801 6/1932 'Lor-ber -61 X 3,287,066 11/1966 Billings 299-37 3,303,899 2/1967 Jones et al. -299 3,305,034 2/1967 Koeln 175-299 3,326,303 6/1967 Jones 173-102 X ERNEST R. PURSER, Primary Examiner. 

